Meeting Abstract
Grass shrimp of the genus Palaemonetes are visual animals, which use their eyes for predation, defense, and orientation. However, work on their visual physiology is dated and comparative studies on sympatric species are absent. This study aimed to investigate the visual physiology of Palaemonetes vulgaris through the use of electroretinogram (ERG) recordings. ERG data was used to model multiple spectral classes in shrimp tested under dark and orange chromatic adaptation and assess irradiance sensitivity with V-logI curves. P. vulgaris were found to be dichromatic, consistent with earlier work that described a broad peak at 540 nm and a narrow peak at 390 nm. The primary peak was clearly seen in dark-adapted animals in the green spectrum at 531 nm. Under orange chromatic-adaptation a UV peak emerged at 390 nm. As well as being a narrower peak shape, there was a 10 nm wavelength discrepancy in the peak wavelength of the green visual pigment compared to earlier work. The UV visual pigment was consistent with previous studies. In addition to spectral sensitivity, irradiance sensitivity measurements were taken at 530 nm in P. vulgaris, as well as in the closely related species P. pugio. These species are found sympatrically, but tend to separate by salinity and substrate in their natural habitats. We found that there is no significant difference between the irradiance sensitivities of the two species when they are maintained in the same conditions. Thus, any differences in habitat do not appear to be reflected in visual physiology.
